Concerning, (from Hank):
"Roy - Bob -- I am uncomfortable about saying that "35 volt" capacitors are
the solution. Now it turns out that in general 35 volt caps will have higher
ripple current ratings than 16 volt caps - BUT there is a world of
difference between different capacitor vendors and ebven different product
line from one vendor.
As Bob knows , I did a fairly extensive SPICE analysis of the 5 volt supply
in the Orion(s) and the real issue was ripple current and thus life of the
capacitor. TT 's first approach was just to use "lower ESR" capacitors - BUT
that still did not resolve the issue - again RIPPLE current ratings are the
issue and that plays into life of the capacitor just as heavy users are
finding...(etc.)"
Hank,
Thanks for your good info and discussions. Now - back to the real world -
what are we talking about for the real, permanent cure? Obviously caps are
available which can handle hundreds of times the ripple current on that
little pc board. We could redesign for a bigger board which can accept a
"big" electrolytic. Or remote locate a high-ripple-rated cap near to the
present board with 'long' leads. By the way, what exactly is the SOURCE of
such high ripple currents in this application? (It certainly isn't ac from
the power lines).
73, Roy K6XK
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